1. Field of the Invention
The present invention relates to a manhole cover assembly, and, more particularly, to a manhole security system.
2. Description of the Related Art
Access to underground sewer and utility systems are typically governed by removal of a manhole cover to gain entry to the utility. Examples of manhole covers include concrete that is shaped to cover a hole, the removal of which allows access to the underground system. Metal manhole cover systems, typically of cast iron having a circularly shaped cover, are commonly used to provide access to the underground system. Even though the weight of the manhole cover can exceed 100 lbs, the weight itself is not sufficient deterrent to prevent access by those that are not authorized to gain access.
One system of security, often utilized when high ranking dignitaries are to take a specified street route, includes the welding of manhole covers to their frames to prevent the underground system from being utilized by individuals wishing to gain access to the intended travel route. Another method of securing manhole covers is to utilize pad locks, which leads to logistical problems relative to the administrative burden of tracking keys for the locks.
Yet another method used to secure manholes is to use bolts with specially shaped heads that require special sockets or wrenches that correspond to the shaped heads for both installation and removal. These have the disadvantage of requiring the special tool for the installation and that they can be removed and replaced without any evidence of access to the underground system.
In a culture where terrorists can strike or rowdy celebrants may remove covers to disrupt traffic flow a cost effective security method for locking manhole covers is needed.